CBSE Questions for Class 12 Medical Physics Dual Nature Of Radiation And Matter Quiz 1 - MCQExams.com

A free particle with initial kinetic energy $$E$$ and de-broglie wavelength $$\lambda$$ enters a region in which it has potential energy $$U$$. What is the particle's new de-Broglie wavelength?
  • $$\lambda (1-U/E)^{-1/2}$$
  • $$\lambda (1-U/E)$$
  • $$\lambda (1-U/E)^{-1}$$
  • $$\lambda (1-U/E)^{1/2}$$
In which of the following photocell is not used?
  • Burglar alarm
  • Television camera
  • Automatic street lights
  • Vacuum cleaner
If the $$KE$$ of a free electron doubles then its de-Broglie wavelength changes by a factor
  • $$\displaystyle\dfrac{1}{2}$$
  • $$\displaystyle\dfrac{1}{\sqrt 2}$$
  • $$\displaystyle2$$
  • $$\displaystyle\sqrt 2$$
The ratio of the energy of a photon of $$2000 \mathring { A } $$ wavelength  to that of $$4000\mathring { A } $$ wavelength is :
  • $$1/4$$
  • $$4$$
  • $$1/2$$
  • $$2$$
If a photon has velocity $$c$$ and frequency $$v$$, then which of the following represents its wavelength
  • $$\dfrac {hc}{E}$$
  • $$\dfrac {hv}{c}$$
  • $$\dfrac {hv}{c^2}$$
  • $$hv$$
The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately: 
  • 540 nm
  • 400 nm
  • 310 nm
  • 220 nm
Photon of frequency $$'v\ '$$ has a momentum associated with it. If $$'c\ '$$ is the velocity of light, the momentum is 
  • $$v/c$$
  • $$hvc$$
  • $$hv/c$$$$^{2}$$
  • $$hv/c$$
A Laser light of wavelength $$660 \,nm$$ is used to weld Retina detachment. If a Laser pulse of width $$60\,ms$$ and power $$0.5\,kW$$ is used, the approximate number of photons in the pulse are:
[Take Planck's constant $$h=6.62\times 10^{-34}Js$$]
  • $$10^{20}$$
  • $$10^{18}$$
  • $$10^{22}$$
  • $$10^{19}$$
For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship?
  • An electron
  • A proton
  • An $$\alpha-particle$$
  • A dust particle
If electron charge e, electron mass m, speed of light in vacuum c and Planck's constant h are taken as fundamental constant h are taken as fundamental quantities, the permeability of vacuum $$\mu_0$$ can be expressed in units of
  • $$\left (\dfrac {mc^2}{he^2}\right )$$
  • $$\left (\dfrac {h}{me^2}\right )$$
  • $$\left (\dfrac {hc}{me^2}\right )$$
  • $$\left (\dfrac {h}{ce^2}\right )$$
If the de Broglie wavelengths associated with a proton and an $$\alpha -$$ particle are equal, then the ratio of velocities of the proton and the $$\alpha -$$ particle will be:
  • $$1:4$$
  • $$1:2$$
  • $$4:1$$
  • $$2:1$$
De-Broglie wavelength of an electron accelerated by a voltage of 50 V is close to: $$(|e|=1.6 \times 10^{-19} C, m_e=9.1 \times 10^{-31}kg, h=6.6 \times 10^{-34} Js).$$ 
  • $$0.5 \mathring {A} $$
  • $$1.7 \mathring {A} $$
  • $$2.4 \mathring {A} $$
  • $$1.2 \mathring {A} $$
The de-Broglie wavelength $$(\lambda_{B})$$ associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state $$(\lambda_{G})$$ by :
  • $$\lambda_{B} = \lambda_{G}/3$$
  • $$\lambda_{B} = \lambda_{G}/2$$
  • $$\lambda_{B} = 2\lambda_{G}$$
  • $$\lambda_{B} = 3\lambda_{G}$$
Two electrons are moving with non-relativistic speeds perpendicular to each other. If corresponding de Broglie wavelengths are $${ \lambda  }_{ 1 }$$ and $${ \lambda  }_{ 2 }$$, their de Broglie wavelength in the frame of reference attached to their centre of mass is:
  • $${ \lambda }_{ CM }={ \lambda }_{ 1 }={ \lambda }_{ 2 }\quad $$
  • $$\cfrac { 1 }{ { \lambda }_{ CM } } =\cfrac { 1 }{ { \lambda }_{ 1 } } +\cfrac { 1 }{ { \lambda }_{ 2 } } $$
  • $${ \lambda }_{ CM }=\cfrac { 2{ \lambda }_{ 1 }{ \lambda }_{ 2 } }{ \sqrt { { { \lambda }_{ 1 } }^{ 2 }+{ { \lambda }_{ 2 } }^{ 2 } } } $$
  • $${ \lambda }_{ CM }=\left( \cfrac { { \lambda }_{ 1 }+{ \lambda }_{ 2 } }{ 2 } \right) $$
An electron (mass $$m$$) with initial velocity $$\vec { v } ={ v }_{ 0 }\hat { i } +{ v }_{ 0 }\hat { j } $$ is an electric field $$\vec { E } =-{ E }_{ 0 }\hat { k } $$. If $${ \lambda  }_{ 0 }$$ is initial de-Broglie wave length at time $$t$$ is given by
  • $$\cfrac { { \lambda }_{ 0 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ 2{ m }^{ 2 }{ v }_{ 0 }^{ 2 } } } } $$
  • $$\cfrac { { \lambda }_{ 0 }\sqrt { 2 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } } $$
  • $$\cfrac { { \lambda }_{ 0 } }{ \sqrt { 2+\cfrac { { e }^{ 2 }{ E }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } } $$
  • $$\cfrac { { \lambda }_{ 0 } }{ \sqrt { 1+\cfrac { { e }^{ 2 }{ E }_{ 0 }^{ 2 }{ t }^{ 2 } }{ { m }^{ 2 }{ v }_{ 0 }^{ 2 } } } } $$
The allowed energy for the particle for a particular value of n is proportional to :
  • $$\mathrm{a}^{-2}$$
  • $$\mathrm{a}^{-3/2}$$
  • $$\mathrm{a}^{-1}$$
  • $$\mathrm{a}^{2}$$
A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30$$mW$$and the speed of light is $$3\times 10^{8}m/s$$. The final momentum of the object is:
  • $$0.3\times 10^{-17}kgms^{-1}$$
  • $$1.0\times 10^{-17}kg ms^{-1}$$
  • $$3.0\times 10^{-17}kgms^{-1}$$
  • $$9.0\times 10^{-17}kgms^{-1}$$
Emission of photoelectrons will not take place light if two different frequencies, whose photons have energy 1 electron volt and 2.5 electron volt are incident one by one on a metal surface of work function 0.5 electron volt. The ratio of maximum energy of emitted electrons will be ?
  • 1:4
  • 4:1
  • 1:2
  • 2:1
The speed of the particle that can take discrete values is proportional to
  • $$\mathrm{n}^{-3/2}$$
  • $$\mathrm{n}^{-1}$$
  • $$\mathrm{n}^{1/2}$$
  • $$n$$
Light of wavelength $$\displaystyle { \lambda  }_{ ph }$$ falls on a cathode plate inside a vacuum tube as shown in the figure. The work function of the cathode surface is $$\displaystyle \phi $$ and the anode is a wire mesh of conducting material kept at a distance d from the cathode. A potential difference V is maintained between the electrodes. If the minimum de Broglie wavelength of the electrons passing through the anode is $$\displaystyle { \lambda  }_{ e }$$, which of the following statement(s) is(are) true?
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  • $$\displaystyle { \lambda }_{ e }$$ increases at the same rate as $${ \lambda }_{ ph }$$ for $$\lambda_{ph} < hc / \phi$$
  • $$\displaystyle { \lambda }_{ e }$$ is approximately halved, if d is doubled
  • $$\displaystyle { \lambda }_{ e }$$ decreases with increase in $$\displaystyle \phi $$ and $$\displaystyle { \lambda }_{ ph }$$
  • For large potential difference $$\displaystyle \left( V>>\phi /e \right) { \lambda }_{ e }$$ is approximately halved if V is made four time
Electrons of mass m with de-Broglie wavelength $$\lambda$$ fall on the target in an X-rays tube. The cutoff wavelength $$(\lambda_0)$$ of the emitted X-rays is
  • $$\lambda_0=\lambda$$
  • $$\lambda_0=\dfrac{2mc\lambda^2}{h}$$
  • $$\lambda_0=\dfrac{2h}{mc}$$
  • $$\lambda_0=\dfrac{2m^2c^2\lambda^3}{h^2}$$
A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is ($$C=$$ Velocity of light)
  • $$\frac {2E}{C^2}$$
  • $$\frac {E}{C^2}$$
  • $$\frac {E}{C}$$
  • $$\frac {2E}{C}$$
Light of wavelength $$500\ nm$$ is incident on a metal with a work function $$2.28\ eV$$. The de Borglie wavelength of the emitted electron is:
  • $$\leq 2.8 \times 10^{-12}m$$
  • $$< 2.8 \times 10^{-10}m$$
  • $$< 2.8 \times 10^{-9}m$$
  • $$\geq 2.8 \times 10^{-9}m$$
If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is :
  • 25
  • 75
  • 60
  • 50
Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?
An electron is accelerated from rest through a potential difference of $$V$$ volt. If the de Broglie wavelength of the electron is $$1.227 \times 10^{-2} nm$$, the potential difference is :
  • $$10^2V$$
  • $$10^3V$$
  • $$10^4V$$
  • $$10V$$
An electron of mass $$m$$ and a photon have same energy $$E$$. The ratio of de-Broglie wavelength associated with them is:
  • $$\dfrac { 1 }{ c } { \left( \dfrac { E }{ 2m } \right) }^{ \dfrac { 1 }{ 2 } }$$
  • $${ \left( \dfrac { E }{ 2m } \right) }^{ \dfrac { 1 }{ 2 } }$$
  • $$c{ \left( 2mE \right) }^{ \dfrac { 1 }{ 2 } }$$
  • $$\dfrac { 1 }{ c } { \left( \dfrac { 2m }{ E } \right) }^{ \dfrac { 1 }{ 2 } }$$

    ($$c$$ being velocity of light)
The wavelength $$\lambda _{e}$$ of an electron and $$\lambda _{p}$$ of a photon of same energy E are related by :
  • $$\lambda _{p}\propto \lambda _{e}^{2}$$
  • $$\lambda _{p}\propto \lambda _{e}$$
  • $$\lambda _{p}\propto \sqrt{\lambda _{e}}$$
  • $$\displaystyle \lambda _{p}\propto \dfrac{1}{\sqrt{\lambda _{e}}}$$
If the momentum of an electron is changed by $$P$$, then the de-Broglie wavelength associated with it changes by $$0.5%$$. The initial momentum of electron will be :
  • $$400P$$
  • $$\cfrac{P}{200}$$
  • $$100P$$
  • $$200P$$
If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is:
  • 25%
  • 75%
  • 60%
  • 50%
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
De Broglie wavelength $$\lambda$$ associated with neutrons is related with absolute temperature T as:
  • $$\lambda \propto T$$
  • $$\lambda \propto \frac{1}{T}$$
  • $$\lambda \propto \frac{1}{\sqrt{T}}$$
  • $$\lambda \propto T^2$$
If we assume kinetic energy of a proton is equal to energy of the photon, the ratio of de Broglie wave length of proton to photon is proportional to :
  • $$\displaystyle E$$
  • $$\displaystyle { E }^{ { -1 }/{ 2 } }$$
  • $$\displaystyle { E }^{ { 1 }/{ 2 } }$$
  • $$\displaystyle { E }^{ { 3 }/{ 2 } }$$
If velocity of a particle is three times of that of electron and ratio of de Broglie wavelength of particle to that of electron is $$1.814 \times 10^{-4}$$. The particle will be :
  • Neutron
  • Deutron
  • Alpha
  • Tritium
Monochromatic light of wavelength $$3000\overset {\circ}{A}$$ is incident on a surface area $$4\ cm^{2}$$. If intensity of light is $$150\ mW/m^{2}$$, then rate at which photons strike the target is
  • $$3\times 10^{10}/s$$
  • $$9\times 10^{13}/s$$
  • $$7\times 10^{15}/s$$
  • $$6\times 10^{19}/s$$
The de Broglie wavelength of a neutron when its kinetic energy is $$K$$, is $$\lambda$$. What will be its wavelength when its kinetic energy is $$4K $$?
  • $$\dfrac{\lambda}{4}$$
  • $$\dfrac{\lambda}{2}$$
  • $$2\lambda$$
  • $$4\lambda$$
The photoelectric threshold energy of certain metal is 3 eV. If light of wavelength 3000 $$A^{o}$$ is incident on the metal, then :
  • Electrons will be emitted
  • Positrons will be emitted
  • Protons will be emitted
  • Electrons will not be emitted
An electron beam after collision with the target produces X-rays of wavelength $$4 A^0$$. The velocity of the electron beam is
  • $$3.31\times 10^{7}m/s$$
  • $$6.31\times 10^{7}m/s$$
  • $$8.31\times 10^{7}m/s$$
  • $$9.31\times 10^{7}m/s$$
The momentum of a proton is p. The corresponding wavelength is
  • h/p
  • hp
  • p/h
  • $$\sqrt{hp}$$
Moving with the same velocity, one of the following has the longest de Broglie wavelength
  • $$\beta -$$particle
  • $$\alpha -$$particle
  • proton
  • neutron
A photon of frequency $${\text{x}}$$ has an energy
  • $$\dfrac{h}{x^{2}}$$
  • $$\dfrac{x}{h}$$
  • $$hx$$
  • $$hx^{2}$$
The wavelength of matter waves does not depend on
  • Momentum
  • Velocity
  • Mass
  • Charge
De-Broglie wavelength depends on
  • Mass of the particle
  • Size of the particle
  • Material of the particle
  • Shape of the particle
If the energy and momentum of a photon are E and P respectively, then the velocity of photon will be:
(one or more than one correct)
  • $$E/P$$
  • $$(E/P)^{2}$$
  • $$EP$$
  • $$3\times 10^{8}m/s$$
The effective mass of photon in microwave region, visible region and x -ray region is in the following order:
  • X-rays > Visible > Microwave
  • Microwave > X-rays > Visible
  • X-rays > Microwave > Visible
  • Microwave > Visible> X-ray
Matter waves are:
  • Electromagnetic waves
  • Mechanical waves
  • Either mechanical or electromagnetic waves
  • Neither mechanical nor electromagnetic waves
The frequency of a photon associated with an energy of 3.31 eV is (given h$$=6.625\times 10^{-34}$$ Js)
  • $$0.8\times 10^{15}$$
  • $$1.6\times 10^{15}$$
  • $$3.2\times 10^{15}$$
  • $$8.0\times 10^{15}$$
A proton when accelerated through a potential difference of  V volt has a wavelength $$\lambda $$ associated with it. An $$\alpha  $$ - particle in order to have the same wavelength $$\lambda $$ must be accelerated through a p.d. of
  • V/8 volt
  • V/4 volt
  • V volt
  • 2V volt
The wavelength associated with an electron having kinetic energy is given by the expression:
  • $$h/\sqrt{2mE}$$
  • $$2h/mE$$
  • $$2 mhE$$
  • $$\dfrac{2\sqrt{2mE}}{h}$$
De Broglie wavelength ‘$$\lambda$$ ’ is proportional to
  • $$\dfrac{1}{\sqrt{E}}$$ for photons and $$\dfrac{1}{E}$$ for particles
  • $$\dfrac{1}{E}$$ for photons and $$\dfrac{1}{\sqrt{E}}$$ for particles
  • $$\dfrac{1}{E}$$ for both photons and particles in motion
  • $$\dfrac{1}{\sqrt{E}}$$ for both photons and particles
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